1. Technical Field
The present invention relates to hydrogen supply equipment that returns hydrogen stored as a liquid to a normal temperature, and supplies the hydrogen at a normal temperature to equipment that uses hydrogen at a normal temperature.
2. Related Art
Currently used hydrogen supply equipment stores liquid hydrogen in a low-temperature storage chamber, heats and vaporizes the liquid hydrogen, and supplies the resulting gas to a device connected at a later stage. For example, when manufacturing quartz glass with a high degree of purity, techniques such as VAD or OVD may be used. Both of these techniques involve (i) generating SiO2 through a hydrolysis reaction in a flame achieved by supplying a silicide such as SiCl4 to an oxyhydrogen flame fueled by supplying hydrogen and oxygen to a burner, (ii) depositing the silicon dioxide to form a porous base material, and (iii) heating the porous base material in an electric furnace to form transparent quartz glass with a high degree of purity.
The hydrogen used here is produced at a normal temperature or stored at a normal temperature. One idea involves liquid hydrogen as backup hydrogen when the supply of the above hydrogen is stopped. Another option involves setting all of the hydrogen supplies to be hydrogen obtained by vaporizing liquid hydrogen. In manufacturing equipment using the VAD or OVD techniques, the flow rate of the gas supplied to the burners is controlled by a mass flow controller (MFC).
In equipment using hydrogen produced at a normal temperature, when switching to hydrogen obtained by vaporizing liquid hydrogen due to a stoppage of the hydrogen supply, a change of about 1% was seen in the actual flow rate of the hydrogen. Furthermore, even when vaporized liquid hydrogen was already being used, the actual flow rate of the hydrogen changed when the amount of hydrogen changed. In particular, when manufacturing quartz glass for optical fiber, this change in the actual flow rate of the hydrogen causes a change in the flame temperature, which affects the hydrolysis reaction of the SiCl4 or the like, and also causes a change in the lifting speed of the base material, which affects the diameter of the base material. These effects lead to an increase in the rate of defective devices.